This blog devotes a lot of digital real-estate to cool experiments on art and artifacts that are non-invasive, or at least minimally so. So I’ve got to admit that I was not particularly overwhelmed by the breathless reports last week in a myriad of media about a project to drill 14 holes into a Vasari painting in order to search for a possibly hidden da Vinci below. The articles were subsequent to a press release by National Geographic on March 12, which was presumably trying to raise interest in a documentary about the project airing a few days later (March 18). Yesterday the well-respected Art-Info published an interesting take-down of the drilling project, entitled “The Search for the Lost Da Vinci Fresco: Serious Science or Irresponsible Hype?” The piece pointed to a protest-petition against the project signed by 530 members of the museum community, including high-profile curators at the Met and the Louvre. According to the Art-Info article, none of these critical folks got face-time in the National Geographic Channel documentary. This is how the writer Kate Deimling put it: “”Finding the Lost Da Vinci,” which aired on the National Geographic Channel on March 18, certainly looked like an infomercial for the project. The program’s narrator describes opposition to the drilling as a “media feeding frenzy” and an “attack from the press,” but none of the experts opposed to it is interviewed or even mentioned by name. Instead, scientists in lab coats decry the opposition to their work and are then seen boring holes into the painting while dramatic music plays.” The Art-Info piece also voices criticism from the conservation science community, namely that the pigments detected by the drilling project might be from brick instead of paint. Another criticism is that non-invasive analytical equipment (such as newer radar technologies) should be used instead of destructive...

In 1932, David Alfaro Siqueiros got kicked out of Mexico for his political leanings so the artist spent six months in Los Angeles, California, where he produced a controversial mural called América Tropical. Siqueiros may not be as well-known as his teacher and contemporary Diego Rivera, but these two, along with José Orozco, formed “Los Tres Grandes,” the big three Mexican muralists of the early 20th century. During his stint in LA, Siqueiros was asked to paint a mural on a second story wall that overlooked Olvera Street, which was–and still is–a romanticized, somewhat kitschy Mexican market set up for tourists. The idea was for Siqueiros to produce something that celebrated tropical America. The expectation was probably that it might be a romanticized vision of Mexico—just like the street below. Instead Siqueiros, who was a die-hard Communist, produced a profoundly political piece of art: A crucified indigenous Mexican is at the forefront of the mural, with an American Eagle flying ominously above. A sharp shooter approaches from the right with his gun aimed at the Eagle. To say the piece made a splash is a pretty major understatement. Some praised the artwork for the potency of its political and social statement. But city officials were not impressed and they pushed successfully for the mural to be whitewashed, explains Leslie Rainer, a senior project officer at the Getty Conservation Institute who is leading the mural’s conservation, and who gave me and a few others a tour of the mural’s site in downtown LA. Since the site is under construction, the mural was covered for protection, as you can see in the photo below. The site will hopefully be reopened for public viewing in the next year or two—fingers crossed. (The $8.95 million project, which is being paid for jointly by the Getty and the City of LA, has faced many delays). Many decades of outdoor exposure as well as the whitewashing took a serious toll on the artwork, Rainer says. The mural has lost all of its color, leaving just a shadow of the original piece. Conservation efforts won’t reintroduce color. This is because there’s no color documentation of the artwork, so any addition of pigment would be a misrepresentation, explains Susan MacDonald, head of GCI Field Projects. Instead, Rainer and the GCI team have carefully cleaned off the whitewashing and reattached parts of the crumbled plaster. They’ve also been doing non-invasive analyses of the artwork, which is an unusual marriage of traditional fresco painting and cement (instead of lime plaster), Rainer says. Siqueiros was really enamored with the (new-to-him) cement and concrete materials that he encountered during his stint...

During most of my visits to Italy, I end up with neck cramps after craning my head backward for hours to look at faraway ceiling frescoes in churches across the country. But last week, I found myself peering directly into the eyes of fresco angels at the top of the Capella Maggiore in Florence’s famous Santa Croce Basilica. These frescoes have been under restoration since 2005 and for the next few months small groups of people can climb the scaffolding to view the artwork up close. The frescoes were painted in the 1380s by Agnolo Gaddi, a disciple of Giotto, one of the architects of the Italian Renaissance. I climbed up the scaffolding with Mariarosa Lanfranchi, a restorer from the Opificio delle Pietre Dure, Italy’s foremost restoration laboratory. She’s been leading the fresco restoration project. One of the first questions she asked me is whether I suffer from vertigo, because we would be going up about 30 meters to reach the very top of the cathedral. Assured that I wouldn’t suffer a panic attack, she began her awesome tour by telling me that the last restoration of part of the church’s frescoes was in the 1930 or 40s. Since then, air pollution has coated the art with a layer of brownish grime. Meanwhile, construction around the city has covered the artwork with little chunks of gypsum dust. The frescoes are porous, and with the city’s high humidity, the gypsum penetrated into the frescoes, giving the artwork a rather speckled look, Lanfranchi explained. To remove the grime and gypsum, the restorers used the “Florentine method,” a combination treatment of ammonium carbonate, followed by a treatment of barium hydroxide, Lanfranchi said. The first step of adding the ammonium carbonate dissolves the unwelcome dust and gypsum (calcium sulfate dihydrate) so that both can be removed from the surface and inside the fresco’s pores. But this first step of the cleaning process also has a downside. It produces some ammonium sulfate, a salt that could be problematic to the frescoes in the future. So the second step of the Florentine method is to add barium hydroxide which turns the problematic ammonium sulfate salt into barium sulfate, which is benign to the artwork. The second step also produces some barium carbonate, which acts as a stabilizing agent (called a consolidant) to the sensitive frescoes. With more than 800 meters squared of fresco surface to restore, Lanfranchi said the scaffolding became like “a second home” to her over the past years. As we walked around the scaffolding she pointed out small details in the frescoes–a bird or an angel or a crack–with the same familiarity...

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